Haptic drivers are devices which may use vibration patterns and waveforms to convey information to a user or operator. Haptic drivers may use piezoelectric actuators (briefly “piezo” actuators) as vibrating components.
Haptic drivers may use different channels for driving external piezo actuators. Such a channel may include a digital-to-analog converter (DAC), a high voltage amplifier and a gain stage. In order to prevent system malfunction due to excessive current demand or give priority to other components, a so-called throttle block may be used which automatically starts to decrease channel gain, e.g. as a result of a monitored voltage drop below a programmed threshold.
A high voltage waveform may be used to generate vibration with a piezo actuator and convey the information to a user. A high voltage amplifier may be used to produce this waveform and a controlled slew rate is desirable during normal operation.
As a result of a battery voltage drop being detected by the throttle block, the gain of the amplifier is reduced automatically to preserve battery life duration; the throttling mechanism may thus result in the gain being reduced automatically with a possible change also in the waveform slew rate. Normal operation of the system may be difficult to achieve under these circumstances.
Changing the slew rate of the high gain amplifier change by taking into account the throttling mechanism may be considered, with proper functionality being however difficult to achieve.
There is a need in the art to overcome the drawbacks outlined in the foregoing, e.g., as related to slew rate control during a battery throttling function aimed at detecting voltage drops and reducing battery current consumption.